1. Field of the Invention
The invention relates to flame-retardant polyester molding compositions and flame-retardant polyamide molding compositions which contain aluminum phosphinates, aluminum hydroxides and/or aluminum phosphonates and/or aluminum phosphates.
2. Description of the Prior Art
Polymers are frequently rendered flame-retardant by adding to them phosphorus-containing or halogen-containing compounds or mixtures of these. Some polymers are processed at high temperatures, e.g. at 250.degree. C. or at higher temperatures. For this reason, many of the known flame retardants are not suitable for applications of this type, because they are too volatile or have insufficient thermal stability. Aluminum salts of phosphinic acids are thermally stable and have already been proposed as flame-retardant additives for polyesters and polyamides (EP-A-0 699 708). However, the phosphinic acids needed for their preparation are relatively expensive. For cost reasons, therefore, there is a need for polymeric molding compositions with phosphinates as flame retardants which can be produced at lower cost.